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Date:   Wed, 24 May 2023 11:00:02 +0200
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     "Jacky Huang" <ychuang570808@gmail.com>,
        "Jiri Slaby" <jirislaby@kernel.org>,
        "Rob Herring" <robh+dt@kernel.org>,
        krzysztof.kozlowski+dt@linaro.org, "Lee Jones" <lee@kernel.org>,
        "Michael Turquette" <mturquette@baylibre.com>,
        "Stephen Boyd" <sboyd@kernel.org>,
        "Philipp Zabel" <p.zabel@pengutronix.de>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        "Tomer Maimon" <tmaimon77@gmail.com>,
        "Catalin Marinas" <catalin.marinas@arm.com>,
        "Will Deacon" <will@kernel.org>
Cc:     devicetree@vger.kernel.org, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-serial@vger.kernel.org, soc@kernel.org, schung@nuvoton.com,
        mjchen@nuvoton.com, "Jacky Huang" <ychuang3@nuvoton.com>
Subject: Re: [PATCH v11 10/10] tty: serial: Add Nuvoton ma35d1 serial driver support
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On Wed, May 24, 2023, at 10:34, Jacky Huang wrote:
> On 2023/5/24 =E4=B8=8B=E5=8D=88 03:42, Jiri Slaby wrote:
>> On 16. 05. 23, 9:52, Jacky Huang wrote:
>>> +static void ma35d1serial_config_port(struct uart_port *port, int fl=
ags)
>>> +{
>>> +=C2=A0=C2=A0=C2=A0 /*
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 * Driver core for serial ports forces a no=
n-zero value for port=20
>>> type.
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 * Write an arbitrary value here to accommo=
date the serial core=20
>>> driver,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 * as ID part of UAPI is redundant.
>>> +=C2=A0=C2=A0=C2=A0=C2=A0 */
>>> +=C2=A0=C2=A0=C2=A0 port->type =3D 1;
>>
>> So this 1 translates to PORT_8250. Why not to use it directly? Or=20
>> something more saner like PORT_16550A?
>>
> It's not actually 8250 or 16550A.
> Can we add the following definition to=20
> 'include/uapi/linux/serial_core.h' and use PORT_MA35 instead?
>
> #define PORT_MA35=C2=A0=C2=A0=C2=A0 124

This was already in a previous version, until Greg commented
that it was probably not needed:

https://lore.kernel.org/lkml/20fc81c9-5517-ce1e-639a-3b425cf27759@gmail.=
com/

Since leaving port->type at PORT_UNKNOWN doesn't work, and almost
all other drivers have something in serial_core.h, it's probably
best to do the same here. Checking the other drivers showed that
drivers/tty/serial/lantiq.c is currently the only exception, it
defines PORT_LTQ_ASC locally, which causes a conflict with
PORT_SPRD.

    Arnd